Abstract
This report deals with the correlation of changes in cardiac metabolism and myocardial contractility of dogs maintained on alcohol for 29 months. Glycerinated heart muscle fibers were used to investigate myocardial contractility in vitro, using an apparatus to record isometric and isotonic contractions. Measurements included maximal tension developed ( P o), maximal rate of tension developed ( dp dt max ), and time to peak tension ( t o). Force-velocity relationship ( V max) was also determined. Biochemical studies revealed significant depression of mitochondrial respiration in heart muscle of dogs exposed to alcohol. Calcium uptake and binding to sarcoplasmic reticulum and its endogenous calcium content were diminished. The activity of intramitochondrial isocitrate dehydrogenase was also decreased. Hemodynamic changes in vivo revealed no significant difference between control animals and dogs maintained on alcohol. In vitro studies on glycerinated heart muscle of dogs exposed to alcohol showed no change in dp dt max , t o or P o . Values for V max were significantly reduced. The results suggest that while the contractile apparatus in heart muscle exposed to alcohol can generate maximal tension, it is deficient in its property to perform external work. Contractile changes in heart muscle of animals exposed to alcohol can exist in vitro, without apparent hemodynamic alterations in vivo. It is not certain whether these changes in vitro are the result of direct action of alcohol on contractile proteins, or develop as a consequence of biochemical changes induced by alcohol.
Published Version
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